|Feb 27, 2007, 02:03 AM|
Landing via FPV..
I figured I'd start a thread on landing via FPV since it was brought up in another thread. I've played plenty of video games and flown MS Flight Sim since it was version 3. Pretty much throughout my childhood I've learned how to fake a 3d environment. For many gamers out there landing FPV shouldn't be a problem. After all we've all played racing games on the Xbox and know exactly how far away some n00b is when we go to gank him with a close range weapon..
Fun aside... Let's start with the first thing. For me I find a couple reference points out at the field that are known. For example. We have this fence out at the field that is about 3 feet high.
I also know this trailer out there is about 10 feet high. The tree next to the trailer is probably about 20 feet high.. Then that Antenna out there is probably 100 feet off the ground... Now keep in mind that all this is just rough estimates of things out there.
So what does all this stuff mean.. Well let's start putting it in perspective...
When I'm flying around basically I'm looking for those objects and using those as reference points. For example let's use this picture to judge things a bit..
As you can see you can kinda guesstimate about how high you are. In this turn my camera is not quite level with the top of the tree. Nor am I flying higher than the top of the tower. Instead I'm flying about mid level with the tower.
Now let's look at a shot form a low flyby of the field. Here we'll see some more detail of what I'm using as reference to 'fake 3d' when I'm flying FPV...
In this picture we can see plenty of rerence points. We have a fence that is about 3' off the ground. I'm about 5'11 tall. The Ramada behind me is about 8' tall. We have a berm at the end of our runway that is about 2' tall. The Trailer out there is about 10' and the tree is 15 feet. If I had to judge about how high I was in this picture I'd say I was anywhere between 5 and 10 feet off the ground. The camera appears to be about level with the top of my head. However due to the tilt of the plane I could be level with the ramada which is about 8' tall. However I'm not close enough to the ground to land since the grass below me is not in GREAT detail. If you recall from MS Flight Sim the same thing happens. When you are high up there is not alot of detail. As you get closer to the ground the computer starts rendering more things in greater detail.
Now let's take this back a few steps. Let's look at what the runway looks like when you line up.
Since this is going to be a fly by.. Here is what I am keeping in mind when flying. I have picked a single point on the runway and I'm using that as my aim point or target. If I was going to land that is where I would try to touch down at. There is a berm I have to fly over to get to the runway. That berm is about 2' high. I also need to know where the end of my runway is at, really important if this was a real landing .. I'm also keeping in mind which way I'm going to go, and which ways I can abort. In this case I'm going to break to the left if anything happens..
Now let's look at the nitty gritty! This isn't one of the most perfect landings to judge.. This is good and bad. First off we'll start with this next frame grab..
As we can see in this grab above things look good. I have the path we're going to take in purple. I am going to aim for my target landing spot marked in Green. I've also decide which way I'm going to go if I have to abort in cyan. The berm for the field is here in yellow. At this point I'm using the tree line and the fence as height markers. From here I should be able to manage my throttle and elevator and land on my target. As many of us probably know if you start REALLY feeding in elevator then you probably want to start bringing up your airspeed.
Now the neat part about my field is by having the two berms out there I can use them as a sorta VASI System as you can see in this next frame grab.
For those that fly the real stuff.. Ya'll know the saying Red, Red, You're Dead. In this case I decided to power up and give the plane a bit of up elevator. I then carried my plane using power to the runway..
Here in this frame above I can see I'm clearing the 2' berm. The next thing I take note of is the 8' ramada and the 3' fence. I'm also keeping the end of the runway in mind. From here things look good and I'm going to decrease the power and go for my targeted landing spot...
In the frame above, I'm going to commit to the landing. You can see the 8' ramada in the background and how the 3' fence is starting to fit into the picture. At this point I'm starting to see ground detail. I'm still about 4-5 feet of the ground from best guess. I'm not quite level with the fence and I'm just below the ramada. I'm about 6' and you can see that I'm pretty much level with my head. At this point I'm still holding for my landing zone.. Although instead of a circle I'm now allowing it to become an elliptical touchdown zone.
In our last picture above we can see motion blurring starting to occur very rapidly. This is a clue that YOU'RE CLOSE TO THE GROUND ... As soon as I see that I'm level with the 3' fence my power is completely off and I have started my flare for landing. At this point I'm putting in up elevator until I see the plane has come in contact with the ground. I'm also keeping the end of the runway in mind just in case I have to make a sudden turn.
It does take a few times to get used to landing via FPV. I'd highly suggest running a few low fly-by's of the runway to get used to it. I can not stress how important it is to review recordings of your external flights. Especially when going over how to land the plane.
If anyone else has any techniques on how they land via FPV and what they are looking for.. PLEASE feel free to add them.
|Feb 27, 2007, 05:30 AM|
I haven't yet landed FPV, (gotta give my spotters some stick time) but I never had much problem landing full sized planes until the day I soloed. On that day I taught myself a new technique that works for me. It relates to this since it involves judging height under difficult conditions.
I knew I was going to solo the next time I flew because my instructor was about to get out of the plane on the previous flight, but had never told me to get my physical. I went and got my physical but the next two or three weeks had impossible weather. Finally we got a day with heavy overcast and no wind.
The problem was that we were landing on packed snow. I had no difficulty with the skis, but under the shadowless lighting from the overcast sky I couldn't tell how high I was. The ground was uniformly white and I couldn't see any texture. I came down pretty firmly on the first landing, and the second was only a little better.
On the third landing I focused on the far edge of the runway. I had been judging height by looking at the ground, now I looked at the far end of the field and I could see the ground come up more or less by a sense of perspective, as if the ground were a big square and I could see it as if I were moving into an edge on view. A bit hard to describe but it came natural when I concentrated on the far end of the runway, instead of looking at the ground.
My instructor got out after that one and on my solo I could hear the backs of the skis touch the ground a good hundred yards before the plane settled.
I am going to give it a try when our field reopens. When you are in a plane you have your full peripheral vision to help and in FPV you don't but it should work. I've been flying my simulators all winter, mostly G2, which is much harder to land than G3 or 3.5 but as yet I haven't got a really solid feel for speed. My landings are gentle, but involve long, low bounces. That's should not be a problem with the Easy Star. (I hope)
Another thought, (which has little appeal to me) is glassy water technique. Under some conditions of no wind and no waves it is almost impossible to judge height over glassy water. The standard technique is to set up a nose high, power on rate of descent of less than 200 feet a minute and let the plane land itself. It is hard to bounce on floats and usually your "runway" is as long as you might need, so you can get the plane down with no risk. Never tried it, and only took one float plane lesson. Too expensive these days.
|Feb 27, 2007, 11:51 AM|
Central Valley, California
Joined Feb 2007
This is a great idea for a thread. Tutorials on different nav aspects of FPV flight for the "new blood" coming in will prove popular.
One thing that I have to 100% agree with, is that Flight Simulators DO help in training the mind to interpret distance on a 2D screen. All the stick time I've had on FS9 wasn't going to waste!
|Feb 27, 2007, 02:17 PM|
Before I made my first flight, I practice for a long period, in winter, and learn to fly r/c planes with simulator. I practice FPV and normal flying because I never fly any r/c planes before. I fly two week normally, and begin with FPV. Simulator help me a lot on bot way of flying.
|Feb 27, 2007, 04:52 PM|
having done FPV landings on water, I can say that it's pretty wierd, there is no real sense of scale, and so everything just keeps getting bigger untill suddenly the plane bounces. I think the problem is that the waves can be many different sizes. I have only done 7 or 8 under the hood so far, so I may get better as things go. Right now, I don't have any plane visible in the shot, I may try adjusting things to leave a little nose, and see if that helps.
|Feb 28, 2007, 01:03 PM|
Chevy Chase, MD
Joined May 2006
I think the most crucial aspect in a good fpv landing is how you set up the glide path on final That seems obvious, but remeber, everything looks green from up there, there are no ground navigation markings, and it isn't that easy to know when to turn from base to final and what altitude you should be to start final. I totally agree with typicalaimster that it is so helpful to record and review your video feeds to really learn the lay of the land. In my experience, if you've set your final up at the right altitude and heading, all you have to do is point the nose at the point of the runway you want to land and the plane will almost land itself. On the other hand, a poor final glide path usually makes landings adventurous. So...learn your field's landmarks from up above and practice those final approaches over and over. Those are my $0.02.
|Feb 28, 2007, 05:29 PM|
Joined Nov 2004
Four FPV flights
If direct link click does not work, use Save As... command - it works. Just in case.
Here is FPV flight on Rogallo-kind deltaplane (with FPV landing, 12 Mb):
This FPV flight on flying wing (with FPV landing, but last seconds was droped out, 10 Mb):
Inside is the long flight over forest and field (deltaplane, 15 MB):
Finally below is the amazing flight over hundreds of suburbian homes and landing between them (deltaplane, 4 Mb).